Method and apparatus for retrieving units from a storage system

ABSTRACT

A load handling device is disclosed for retrieving, transporting, and delivering containers in a storage system having a grid structure formed of two substantially perpendicular sets of rails or tracks located above stacks of containers. An exemplary load handling device can include a wheel assembly, a container receiving space, and a plurality of vehicle modules. The wheel assembly can include a first set of wheels to guide movement of the load handing device in a first direction and a second set of wheels to guide movement of the load handing device in a second direction. Each of the vehicle modules can include a container lifting means arranged to lift a container into the container receiving space and each of the vehicle modules can be moveable to adjust the spacing of the containers in the load handling device.

The present invention relates to apparatus for retrieving units form astorage system. In particular, but not exclusively, the inventionrelates to robotic devices for handling storage containers or bins in astore comprising a grid of stacked units.

This application claims priority from UK Patent Application NoGB1616597.9 filed on 30 Sep. 2016, hereby incorporated by reference.

Some commercial and industrial activities require systems that enablethe storage and retrieval of a large number of different products. Oneknown system for the storage and retrieval of items in multiple productlines involves arranging storage bins or containers on rows of shelvesarranged in aisles. Each bin or container holds a plurality of productsof one product type. The aisles provide access between the rows ofshelves, so that the required products can be retrieved by operatives orrobots that circulate in the aisles. It will be appreciated, however,that the need to provide aisle space to access the products means thatthe storage density of such systems is relatively low. In other words,the amount of space actually used for the storage of products isrelatively small compared to the amount of space required for thestorage system as a whole.

In an alternative approach, which offers a significant improvement instorage density, containers are stacked on top of one another and thestacks are arranged in rows. The containers are accessed from above,removing the need for aisles between the rows and allowing morecontainers to be stored in a given space.

Methods of handling containers stacked in rows have been well known fordecades. In some such systems, for example as described in U.S. Pat. No.2,701,065, free-standing stacks of containers are arranged in rows inorder to reduce the storage volume associated with storing suchcontainers while still providing access to a specific container ifrequired. Access to a given container is made possible by providingrelatively complicated hoisting mechanisms which can be used to stackcontainers and to remove given containers from stacks. The cost of suchsystems are, however, impractical in many situations and they havemainly been commercialized for the storage and handling of largeshipping containers.

The concept of using freestanding stacks of containers and providing amechanism to retrieve and store specific containers has been developedfurther, for example as described in EP 0 767 113 B (Cimcorp). Cimcorpdiscloses a mechanism for removing a plurality of stacked containersusing a robotic load handler in the form of a rectangular tube which islowered around the stack of containers, and which is configured to beable to grip a container at any level in the stack. In this way, severalcontainers can be lifted at once from a stack. The movable tube can beused to move several containers from the top of one stack to the top ofanother stack, or to move containers from a stack to an externallocation and vice versa. Such systems can be particularly useful whereall of the containers in a single stack contain the same product (knownas a single-product stack). The load handler can be used to movecontainers between single-product stacks, for example to add a pluralityof containers containing a single3(a) type of product to the store, andto pick up one or more containers from two or more single-product stacksto create a multi-product output stack. An example of this is thepicking of vegetable crates in a central warehouse to create amulti-product order for delivery to retail stores.

In the system described in Cimcorp, the height of the tube has to be asleast as high as the height of the largest stack of containers, so thatthat the highest stack of containers can be extracted in a singleoperation. Accordingly, when used in an enclosed space such as awarehouse, the maximum height of the stacks is restricted by the need toaccommodate the tube of the load handler. Furthermore, the system is notwell adapted for the selection of a single container from amulti-product stack.

Online retail businesses selling multiple product lines, such as onlinegrocers and supermarkets, require systems that are able to store tens oreven hundreds of thousands of different product lines. The use ofsingle-product stacks in such cases can be impractical, since a verylarge floor area would be required to accommodate all of the stacksrequired. Furthermore, it can be desirable only to store smallquantities of some items, such as perishables or infrequently-orderedgoods, making single-product stacks an inefficient solution.

Accordingly, for some applications, the use of multi-product stacks, inwhich the containers making up each stack may hold different products,is favoured in order to maximise the storage density of the system. Thestored items must remain accessible reasonably quickly and easily, sothat a plurality of different items required to fulfil a customer ordercan be picked from the storage system in an efficient way, even if someof the items required are stored in a lower level of a stack, underneathseveral other containers.

International patent application WO 98/049075A (Autostore), the contentsof which are incorporated herein by reference, describes a system inwhich multi-product stacks of containers are arranged within a framestructure. A system of this type is illustrated schematically in FIGS. 1to 4 of the accompanying drawings.

As shown in FIGS. 1 and 2, stackable containers, known as bins 10, arestacked on top of one another to form stacks 12. The stacks 12 arearranged in a grid frame structure 14 in a warehousing or manufacturingenvironment. FIG. 1 is a schematic perspective view of the framestructure 14, and FIG. 2 is a top-down view showing a stack 12 of bins10 arranged within the frame structure 14. Each bin 10 typically holds aplurality of product items (not shown), and the product items within abin 10 may be identical, or may be of different product types dependingon the application.

The frame structure 14 comprises a plurality of upright members 16 thatsupport horizontal members 18, 20. A first set of parallel horizontalmembers 18 is arranged perpendicularly to a second set of parallelhorizontal members 20 to form a plurality of horizontal grid structuressupported by the upright members 16. The members 16, 18, 20 aretypically manufactured from metal. The bins 10 are stacked between themembers 16, 18, 20 of the frame structure 14, so that the framestructure 14 guards against horizontal movement of the stacks 12 of bins10, and guides vertical movement of the bins 10.

The top level of the frame structure 14 includes rails 22 arranged in agrid pattern across the top of the stacks 12. Referring additionally toFIGS. 3 and 4, the rails 22 support a plurality of robotic load handlingdevices 30. A first set 22 a of parallel rails 22 guide movement of theload handling devices 30 in a first direction (X) across the top of theframe structure 14, and a second set 22 b of parallel rails 22, arrangedperpendicular to the first set 22 a, guide movement of the load handlingdevices 30 in a second direction (Y), perpendicular to the firstdirection. In this way, the rails 22 allow movement of the load handlingdevices 30 laterally in two dimensions in the horizontal X-Y plane, sothat a load handling device 30 can be moved into position above any ofthe stacks 12.

The load handling devices 30 are further described in Norwegian patentnumber 317366, the contents of which are incorporated herein byreference. FIGS. 3a and 3b are schematic perspective views of a loadhandling device 30 from the rear and front, respectively, and FIG. 3c isa schematic front perspective view of a load handling device 30 liftinga bin 10.

Each load handling device 30 comprises a vehicle 32 which is arranged totravel in the X and Y directions on the rails 22 of the frame structure14, above the stacks 12. A first set of wheels 34, consisting of a pairof wheels 34 on the front of the vehicle 32 and a pair of wheels 34 onthe back of the vehicle 32, is arranged to engage with two adjacentrails of the first set 22 a of rails 22. Similarly, a second set ofwheels 36, consisting of a pair of wheels 36 on each side of the vehicle32, is arranged to engage with two adjacent rails of the second set 22 bof rails 22. Each set of wheels 34, 36 can be lifted and lowered, sothat either the first set of wheels 34 or the second set of wheels 36 isengaged with the respective set of rails 22 a, 22 b at any one time.

When the first set of wheels 34 is engaged with the first set of rails22 a and the second set of wheels 36 is lifted clear from the rails 22,the wheels 34 can be driven, by way of a drive mechanism (not shown)housed in the vehicle 32, to move the load handling device 30 in the Xdirection. To move the load handling device 30 in the Y direction, thefirst set of wheels 34 is lifted clear of the rails 22, and the secondset of wheels 36 is lowered into engagement with the second set of rails22 a. The drive mechanism can then be used to drive the second set ofwheels 36 to achieve movement in the Y direction.

The load handling device 30 is equipped with a crane device 40. Thecrane device 40 comprises a cantilever arm 42 that extends laterallyfrom the top of the vehicle 32. A gripper plate 44 is suspended from thecantilever arm 42 by four cables 46. The cables 46 are connected to awinding mechanism (not shown) housed within the vehicle 32. The cables46 can be spooled in or out from the cantilever arm 42, so that theposition of the gripper plate 44 with respect to the vehicle 32 can beadjusted in the Z direction.

The gripper plate 44 is adapted to engage with the top of a bin 10. Forexample, the gripper plate 44 may include pins (not shown) that matewith corresponding holes (not shown) in the rim that forms the topsurface of the bin 10, and sliding clips (not shown) that are engageablewith the rim to grip the bin 10. The clips are driven to engage with thebin 10 by a suitable drive mechanism housed within the gripper plate 44,which is powered and controlled by signals carried through the cables 46themselves or through a separate control cable (not shown).

To remove a bin 10 from the top of a stack 12, the load handling device30 is moved as necessary in the X and Y directions so that the gripperplate 44 is positioned above the stack 12. The gripper plate 44 is thenlowered vertically in the Z direction to engage with the bin 10 on thetop of the stack 12, as shown in FIG. 3c . The gripper plate 44 gripsthe bin 10, and is then pulled upwards on the cables 46, with the bin 10attached. At the top of its vertical travel, the bin 10 is accommodatedbeneath the cantilever arm 42 and is held above the level of the rails22. In this way, the load handling device 30 can be moved to a differentposition in the X-Y plane, carrying the bin 10 along with it, totransport the bin 10 to another location. The cables 46 are long enoughto allow the load handling device 30 to retrieve and place bins from anylevel of a stack 12, including the floor level. The vehicle 32 issufficiently heavy to counterbalance the weight of the bin 10 and toremain stable during the lifting process. The weight of the vehicle 32may be comprised in part of batteries that are used to power the drivemechanism for the wheels 34, 36.

As shown in FIG. 4, a plurality of identical load handling devices 30are provided, so that each load handling device 30 can operatesimultaneously to increase the throughput of the system. The systemillustrated in FIG. 4 includes two specific locations, known as ports24, at which bins 10 can be transferred into or out of the system. Anadditional conveyor system (not shown) is associated with each port 24,so that bins 10 transported to a port 24 by a load handling device 30can be transferred to another location by the conveyor system, forexample to a picking station (not shown). Similarly, bins 10 can bemoved by the conveyor system to a port 24 from an external location, forexample to a bin-filling station (not shown), and transported to a stack12 by the load handling devices 30 to replenish the stock in the system.

Each load handling device 30 can lift and move one bin 10 at a time. Ifit is necessary to retrieve a bin 10 (“target bin”) that is not locatedon the top of a stack 12, then the overlying bins 10 (“non-target bins”)must first be moved to allow access to the target bin 10.

Each of the load handling devices 30 is under the control of a centralcomputer. Each individual bin 10 in the system is tracked, so that theappropriate bins 10 can be retrieved, transported and replaced asnecessary.

The system described with reference to FIGS. 1 to 4 has many advantagesand is suitable for a wide range of storage and retrieval operations. Inparticular, it allows very dense storage of product, and it provides avery economical way of storing a huge range of different items in thebins 10, while allowing reasonably economical access to all of the bins10 when required for picking.

For high-volume systems in which speed of operation is critical, it isimportant to maximise the performance of each of the load handingdevices, in terms of speed of operation, battery life, reliability,lifting capacity, stability and so on. It may therefore be desirable toprovide load-handling devices that offer improved performance in one ormore of these areas.

It may also be desirable to increase the number of load handling devicesin use at any one time, to allow an increase in the speed with whichitems can be retrieved from the storage system. For example, theApplicant's co-pending International Patent Application No.PCT/GB2013/051215, the content of which is incorporated herein byreference, describes a storage system in which a plurality of each oftwo different types of load handling device are provided. One type ofload handling device is adapted to lift a plurality of bins from a stackin one operation, to allow a target bin in the stack to be accessed by asingle-bin load handling device of the second type. In such cases, itmay be desirable to reduce the size of the load handling devices inorder to minimise instances in which the optimum movement path for onedevice is hindered by the presence of other devices.

Load handling devices of the type described above are expensive and itis an object of the present invention to reduce the electronics andcontrol mechanisms by providing a single load handling device capable oflifting and carrying multiple containers.

It is against this background that the present invention has beendevised.

According to the invention there is provided a load handling device forlifting and moving containers stacked in a storage system comprising aplurality of rails or tracks arranged in a grid pattern above the stacksof containers, the grid pattern comprising a plurality of grid spacesand each stack being located within a footprint of only a single gridspace, the load handling device being configured to move laterally onthe rails or tracks above the stacks, the load handling devicecomprising a container receiving space located above the rails or tracksin use and a plurality of vehicle modules, the modules comprisingcontainer lifting means arranged to lift a corresponding number ofcontainers as vehicle modules in to the container receiving space.

According to the invention there is further provided a storage systemcomprising: a first set of parallel rails or tracks and a second set ofparallel rails or tracks extending substantially perpendicularly to thefirst set of rails or tracks to form a grid comprising a plurality ofgrid spaces; a plurality of stacks of containers located beneath therails or tracks and arranged such that each stack occupies a footprintof a single grid space; a load handling device as arranged to movelaterally above the stacks on the rails, the load handling devicecomprising a container receiving recess located above the rails and aplurality of vehicle modules, the vehicle modules comprising liftingmeans the lifting means arranged to lift a plurality of containers froma plurality of stacks into the container receiving space.

According to the invention there is further provided a method oftransferring a plurality of containers located within a plurality ofadjacent stacks in a storage system from the storage system to ashipping trolley, the method comprising the steps of: retrieving aplurality of containers from a correspondingly numbered plurality ofstacks; transporting the containers in a load handling device, the loadhandling device comprising a plurality of vehicle modules; deliveringthe containers to a port location; lowering the containers on to acontainer receiving platform; adjusting the spacing of the containersusing adjustment means; and loading the containers on to the shippingtrolley.

A load handling device according to an embodiment of the inventionincludes a container-receiving space into which a plurality ofcontainers can be lifted. The container-receiving space is arrangedbeneath a corresponding number of vehicle modules as containers to belifted, and components such as power components, control components,drive components and lifting components are housed.

By arranging the bulky components of the load handling device above thecontainer-receiving space, the footprint of the load handling device isreduced compared to the cantilever designs shown in FIGS. 3a to 3c anddescribed in NO317366, in which the bulky components are housed in avehicle module disposed to one side of the container-receiving space.Advantageously, the load handling device of the present inventionoccupies the space above a corresponding number of stacks in the frameas vehicle modules and containers to be lifted.

This means that, by virtue of the invention, the efficiency of operationof the storage system can be improved, because the footprint of the loadhandling device allows more containers to be lifted in a singleoperation than a load handling device capable of lifting only onecontainer.

The load handling device preferably includes a set of wheels forsupporting the load handling device above the stacks. For example,lateral movement of the load handling device may be guided by railsdisposed above the frame. The rails may be arranged in a grid pattern,allowing two-dimensional movement of the load handling device in thehorizontal plane. The wheels may engage with the rails. Two sets ofwheels may be provided, with one set being arranged to engage with afirst set of rails to guide movement of the second handling device in afirst direction, and another set being arranged to engage with a secondset of rails to guide movement of the second handling device in a seconddirection.

In an embodiment of the invention, the wheels are arranged at theperiphery of the container-receiving space. The wheels may be driven byone or more motors housed in the vehicle module. Drive may betransferred from the motors in the vehicle module to the wheels by drivetransfer means disposed around the container-receiving space. Forexample, the drive transfer means may comprise a suitable arrangement ofpulleys and drive belts.

One or both set of wheels may be configured to be raised and loweredwith respect to the other set of wheels. One or more wheel lift motorsor other wheel lift devices may be housed in the vehicle module for thispurpose.

The vehicle module may house a plurality of winches or crane devices forlifting a corresponding number of containers as vehicle modules into thecontainer-receiving space. The crane devices may include one or moremotors for lifting the containers, and the or each motor of the or eachcrane device may be housed in the or each vehicle module.

Each crane device may include a gripper device configured to grip acontainer from above. The gripper device may be suspended from cablesthat can be extended and retracted from the vehicle to move the gripperdevice vertically.

In another embodiment, the load handling device is equipped with alifting device arranged to lift a plurality of containers from the stackinto the container-receiving space. The lifting devices may comprise apair of lifting arms, in which case the or each lifting device maycomprise a gripper device mounted between the ends of the arms andarranged to grip a container from above.

In another embodiment, the or each lifting device comprises rods orcables arranged to engage with vertical channels formed in the sidewalls of the containers. The channels may be accessed by apertures in atop face of each container. In such an arrangement, vertically-extendingspaces in the storage system are not necessary.

The rods or cables may carry an anchor mechanism arranged to engagereleasably with a container. For example, the anchor mechanism maycomprise one or more laterally-extendable arms for engaging a surface ofthe container. The anchor mechanism may be operated remotely, forexample by a wire that extends through a tubular bore of the rod orcable.

A load handling device according to another embodiment of the inventioncomprises an upper part, a lower part including a container-receivingspace, and a plurality of winch means for lifting containers into thecontainer-receiving space. The winch means comprise winch motors whichare housed in the upper part, above the container-receiving space. Thelower part includes a wheel assembly to facilitate lateral movement ofthe load handling device with respect to the frame, and the upper partalso includes at least one motor for driving one or more wheels of thewheel assembly.

The lower part may comprise a frame structure for supporting the wheelsof the wheel assembly. The frame structure may be arranged around thecontainer-receiving space. For example, the container-receiving spacemay be bounded on four sides by the frame structure. One or moreelements of the frame structure may be moveable to raise and lower afirst set of the wheels with respect to a second set of the wheels,thereby to facilitate engagement of either the first set of wheels orthe second set of wheels with a first or a second set of rails ortracks, respectively. The moveable elements of the frame structure maybe driven by a motor housed in the upper part of the load handlingdevice.

The load-handling device of the invention is preferably a self-propelledrobot vehicle.

From another aspect, the invention resides in a storage systemcomprising a frame containing a plurality of stacks of containers, andone or more load handling devices as described above. Each load handlingdevice occupies a plurality of grid spaces, corresponding to the areaoccupied by a plurality of stacks of containers.

In another aspect, the invention comprises a storage system comprising aframe containing a plurality of stacks of containers, a first handlingdevice capable of lifting a plurality of containers from a plurality ofstacks in a single operation, and a second handling device capable oflifting a single container and moving the container laterally. The firstand second handling devices are disposed above the frame and areindependently moveable to access different stacks. The second handlingdevice is of the type described above, but occupies a spacecorresponding to only one stack of containers.

In this aspect, the provision of a first handling device capable oflifting a plurality of containers from a plurality of stacks in a singleoperation along with a second handling device capable of lifting asingle container and moving the container laterally provides an optimumsolution when seeking to retrieve and move a large number of containers.In such a case, only a single lifting operations need be carried out toretrieve the plurality of target containers, which greatly increases thespeed and efficiency of the retrieval process compared to prior artarrangements in which only one container can be lifted at a time.

The storage system may further comprise one or more port locations atwhich containers can be removed from and/or added to the storage system.The load handling device of the invention may be capable of transportinga target containers from a plurality of stacks to a port location. Thecontainers may comprise open-topped bins. The containers may be arrangedto interlock or engage with one another in the vertical direction whenformed in a stack.

In a typical application, multiple handling devices may be employed sothat a large number of containers can be lifted and moved simultaneouslyin and around the system. The handling devices may be of differenttypes, and may be selected to balance the cost and energy consumption ofthe system with the speed and flexibility of operation. One benefit ofthe present invention is that, because the load handling devices occupythe space above a plurality of stacks, the efficiency of amultiple-device system can be improved compared to prior art loadhandling device designs which occupy two or more stack spaces to lift asingle container. The gain in efficiency may arise from being able toaccommodate more load handling devices in a given system, fromoptimising the routing of the device, or from a combination of thesefactors.

Preferably the load handling device of the invention occupies a 2×2 gridspace and is capable of retrieving four containers in a singleoperation. Preferably the load handling device comprises four vehiclemodules arranged in a 2×2 arrangement above the container-retrievingspace of the load handling device. Preferably each vehicle modulecomprises a winch or crane lifting device for engaging with a containerat the top of a stack above which the load handling device ispositioned.

Preferably the load handling device carrying the plurality of containersin the container receiving space, may be transported to a position abovea port location under the control of a communications and controlsystem. Once above the port location, the winch or crane lifting meansmay lower the plurality of containers on to a container receivingplatform, the platform comprising means for moving the loweredcontainers on to a container shipping trolley comprising a series ofshelves in substantially a single movement. The process repeats suchthat a container shipping trolley may be filled a shelf at a time inorder to be ready to be loaded on to a vehicle for onward shipment.

Preferred and/or optional features of each aspect of the invention maybe used, alone or in appropriate combination in the other aspects of theinvention also.

FIG. 1 is a schematic perspective view of a frame structure for housinga plurality of stacks of bins in a known storage system;

FIG. 2 is a schematic plan view of part of the frame structure of FIG.1;

FIGS. 3a and 3b are schematic perspective views, from the rear and frontrespectively, of a known load handling device for use with the framestructure of FIGS. 1 and 2, and FIG. 3c is a schematic perspective viewof the known load handling device in use lifting a bin; and

FIG. 4 is a schematic perspective view of a known storage systemcomprising a plurality of load handling devices of the type shown inFIGS. 3a, 3b and 3c , installed on the frame structure of FIGS. 1 and 2.

Embodiments of the present invention will now be described, by way ofexample only, with reference to the remainder of the accompanyingdrawings, in which like reference numerals are used for like features,and in which:

FIG. 5 is a schematic perspective view of a load handling deviceaccording to an embodiment of the invention;

FIGS. 6 and 7 are schematic perspective views of the load handlingdevice of FIG. 5, showing the arrangement of four vehicle modules withinthe load handling device;

FIG. 8 is a schematic perspective view of a storage system comprising aload handling device in accordance with FIG. 5 installed on the framestructure of FIGS. 1 and 2, the load handling device being in situ abovefour stacks of containers of the type to be retrieved;

FIGS. 9 and 10 are schematic perspective views of the storage system andload handling device of FIGS. 6 and 7 showing container lifting meansassociated with each vehicle module engaging with a top container ineach stack;

FIGS. 11 and 12 are side views of the load handling device and stacks ofFIGS. 9 and 10, the lifting means engaged with containers;

FIG. 13 is a schematic perspective view of one form of port location ina storage system showing a receiving platform and transfer mechanism fortransferring delivered containers on to a shipping trolley;

FIG. 14 is a schematic perspective view of the port location of FIG. 13showing two containers being lowered on to the container receivingplatform by the load handling device;

FIGS. 15 and 16 are schematic perspective views of the vehicle moduleswithin the load handling device, showing movement of two of the vehiclemodules to enable the containers to be delivered on to the containerreceiving platform in a position enabling the container transfermechanism to relocate the delivered containers on to the shippingtrolley;

FIGS. 17 and 18 are schematic perspective views of the load handlingdevice in position above a port location in accordance with one form ofthe invention, showing the container lifting means disengaging from thecontainers delivered on to the container receiving platform;

FIG. 19 is a schematic perspective view of the load handling devicehaving completely disengaged from the delivered containers, thecontainers being located on the delivery platform;

FIGS. 20 and 21 are schematic perspective views of the deliveredcontainers in situ on the container receiving platform, delivered by theload handling device of one form of the invention, the deliveredcontainers being transferred via transferring means on to the shippingtrolley; and

FIGS. 22 to 26 are schematic perspective views showing the load handlingdevice, the vehicle modules and the shipping trolley loading system inaccordance with a further form of the invention in which the vehiclemodule spacing within the load handling device remains constant and thecontainer receiving platform comprises two portions, a first portionbeing moveable relative to the second portion such that in use, thevehicle modules lower the containers on to the platforms, a portion ofthe platform moving so as to enable the delivered containers to betransferred to the shipping trolley.

FIG. 5 shows a load handling device 100 according to an embodiment ofthe invention. The load handling device 100 comprises a vehicle 102equipped with a plurality of vehicle modules 103, each module 103comprising winch or crane mechanisms 104 to lift a storage container orbin 106, also known as a tote, from above. The crane mechanisms 104includes winch cables 108 and grabber plates 110. The grabber plates 110are configured to grip the top of the containers 106 to lift them from astack 12 of containers 106 in a storage system of the type shown inFIGS. 1 and 2.

Referring also to FIGS. 6 and 7, the vehicle 102 comprises an upper part112 and a lower part 114.

The lower part 114 is fitted with two sets of wheels 116, 118, which runon rails provided at the top of the frame of the storage system. Atleast one wheel of each set 116, 118 is driven to enable movement of thevehicle 102 in X- and Y-directions respectively along the rails. As willbe explained below, one or both sets of wheels 116, 118 can be movedvertically to lift each set of wheels clear of the respective rails,thereby allowing the vehicle 102 to move in the desired direction.

The wheels 116, 118 are arranged around the periphery of a cavity orrecess 120, known as a container-receiving recess, in the lower part114. The recess 120 is sized to accommodate the or each bin 106 when itis lifted by the crane mechanism 104, as shown in FIGS. 11 and 12. Whenin the recess 120, the bin 106 is lifted clear of the rails beneath, sothat the vehicle 102 can move laterally to a different location. Onreaching the target location, for example another stack 12, an accesspoint in the storage system or a conveyor belt, the bins 106 can belowered from the recess 120 and released from the grabber plates 110.

The upper part 112 of the vehicle 102 houses all of the significantbulky components of the load handling device, as shown in FIGS. 6 and 7.The upper part 112 houses the battery and associated electronics,controllers and communications devices, motors for driving the wheels116, 118, motors for driving the crane mechanism 104, and other sensorsand systems.

In this way, the footprint of the vehicle 102 is larger than the size ofthe bins 106 contained within the recess 120 only enough to accommodatethe wheels 116, 118 either side of the recess 120. In other words, thevehicle 102 occupies a plurality of grid spaces in the storage systemequivalent only to the number of vehicle modules contained within theload handling device 100.

The load handling devices 100 of the invention can also offer improvedstability, increased load handling capacity and reduced weight comparedto the cantilever-type prior art load handling devices 30, because inthe invention the load of the containers is suspended between the pairsof wheels on each side of the vehicle. In contrast, the prior-artdevices 30 must have a relatively heavy vehicle module to counterbalancethe load in the cantilever configuration.

FIGS. 5 to 21 show one embodiment of the invention. The upper part 112of the vehicle 102 houses four vehicle modules 103, each module 103having three main motors: a Z-drive motor 150 used to raise and lowerthe winch cables 108, which are wound onto spools mounted on driveshafts situated at opposite sides of the vehicle 102; an X-drive motorwhich drives the first set of wheels 116, and a Y-drive motor whichdrives the second set of wheels 118. The upper part 112 of the vehiclealso houses a battery 156 to power the motors, and controllers, sensorsand other components as described above with reference to FIGS. 6 and 7.

Drive is transferred from the X- and Y-drive motors to the respectivesets of wheels 116, 118 by means of belt drive mechanisms. The X-drivemotor or motors drive pulleys connected to a short drive shaft thatextends across the vehicle body. Drive is transferred from the shortdrive shaft to each wheel in the first set of wheels 116 by an X drivebelt. The Y-drive motor drives a pulley 170 connected to a long driveshaft that extends across the vehicle body in a direction perpendicularto the short drive shaft. Drive is transferred from the long drive shaftto each wheel in the second set of wheels 118 by a Y drive belt.

The belt-driven wheels 116, 118 are mounted at the bottom of the lowerpart 114 of the vehicle 102. The use of drive belts to transfer drivefrom the motors to the wheels enables the motors to be mounted in theupper part 112 of the vehicle.

In this embodiment, as an example only, the first set of wheels 116 canbe raised clear of the rails or lowered onto the rails by means of awheel positioning mechanism. One form of mechanism may operate asfollows: the wheel 116 is mounted on an arm that is pivotally mounted atits outer end. An inner end of each arm is connected to the lower end ofa respective linkage. The upper ends of both linkages are connected tothe lower end of a common linkage. In turn, the upper end of the commonlinkage is connected to a lever arm that is moved by a motor. Byoperating the motor to draw the common linkage upwards, the first set ofwheels 116 can be raised so that the second set of wheels 118 alone isengaged with the rails, allowing movement of the vehicle 102 in theY-direction. By operating the motor to push the common linkagedownwards, the first set of wheels 116 move downwards to engage with therails and to lift the vehicle so that the second set of wheels 118 islifted clear of the rails. The vehicle 102 can then move in theX-direction.

The wheels 118 of the second set may be mounted to fixed T-piecesdisposed at either end of the lower part 114 of the vehicle 102.

It will be appreciated that the wheels need not be arranged around theperiphery of the cavity or recess. Indeed, multiple sets of wheels maybe provided so as to take advantage of the tracks or rails defining thefootprint of the stacks of containers or bins 10.

FIGS. 8, 9 and 12 show the load handling device 100 with bins 106 beinglifted into the recess 120. FIG. 11 shows the load handling device 100with the bin 106 beneath the device 100 and one grabber plate 110 aboutto engage with one target bin 106. The wheels 116, 118 and theassociated support pieces, linkages and drive belts are arranged aroundthe edges of the recess 120, so that the upper part 112 of the vehicle102 is solidly supported.

Wheels suitable for use as one of the wheels 116, 118 of the loadhandling device 100 may comprise a toothed central channel that forms apulley for cooperating with a drive belt. The channel is bounded by tworubber tyres, which bear upon the rails in use. The wheel can be mountedto an arm by way of an axle (not shown) that extends through an axialhole in the wheel. This wheel design is compact and balanced, tominimise wear, and the tyres serve to keep the drive belt in alignmentin use.

FIG. 13 is a schematic perspective view of one form of port location ina storage system showing a container receiving platform 198 and transfermechanism 200 for transferring delivered containers on to a shippingtrolley 202.

FIG. 14 is a schematic perspective view of the port location of FIG. 13showing two containers 106 being lowered on to the container receivingplatform 198 by the vehicle modules 103 of the load handling device 100.As can be seen in FIG. 14, the spacing of the containers 106 in thecontainer receiving recess 120 does not match the spacing of thecontainer receiving shelves of the container shipping trolley 202.

FIGS. 15 and 16 are schematic perspective views of the vehicle modules103 within the load handling device 100, showing movement of two of thevehicle modules 103 to enable the containers 106 to be delivered on tothe container receiving platform 198 in a position enabling thecontainer transfer mechanism 200 to relocate the delivered containers106 on to the shipping trolley 202.

FIGS. 17 and 18 are schematic perspective views of the load handlingdevice 100 in position above a port location in accordance with one formof the invention, showing the container lifting means 110 disengagingfrom the containers 106 delivered on to the container receiving platform198.

FIG. 19 is a schematic perspective view of the load handling device 100having completely disengaged from the delivered containers 106, thecontainers 106 being located on the delivery platform 198.

FIGS. 20 and 21 are schematic perspective views of the deliveredcontainers 106 in situ on the container receiving platform 198,delivered by the load handling device 100 of one form of the invention,the delivered containers 106 being transferred via transferring means onto the shipping trolley 202.

In use, two of the vehicle modules 103 lower a first two containers 106on to one portion of the container receiving platform 198. Once thefirst two containers 106 are lowered on to the platform, the opposingtwo vehicle modules 103 move within the body of the load handling deviceto a position above a second portion on the container receiving platform198. The vehicle modules 103 lower the two containers 106 on thecontainer lifting means on to the second portion of the platform 198.Once all four of the containers 106 are in the correct position on thecontainer receiving platform 198, the grippers 110 are winched back into the load handling device 100, the vehicle modules reposition and theload handling device 100 is free to be moved under the control of thecommunications and control system to a different location.

The four containers 106 on the container platform 198 are transferred bysuitable transferring means 200 on to the shipping trolley 202. Thetransferring means may comprise a push plate mechanism, a conveyormechanism or any other suitable form of transferring mechanism formoving the containers 106 on to the shipping trolley 202.

It will be appreciated that in the embodiments of the inventiondescribed above, the load handling device is adapted to retrieve fourcontainers 106 in a 2×2 arrangement but that any other arrangement ofcontainers 106 and vehicle modules 103 may be used, for example 1×2,1×3, 2×3, and 3×3 or more may be envisaged. In the case where adifferent number of containers 106 are envisaged, the containerreceiving platform would also need to be adapted to accept thecorresponding number of containers 106.

It will be appreciated that in these different container-vehicle modulearrangements, it may be especially advantageous for the wheels not to bearranged around the periphery of the cavity or recess. Indeed, it may benecessary for multiple sets of wheels to be provided so as to takeadvantage of the tracks or rails defining the footprint of the stacks ofcontainers or bins 10.

FIGS. 22 to 26 are schematic perspective views showing the load handlingdevice 100, the vehicle modules 103 and the shipping trolley 202 loadingsystem 200 in accordance with a further form of the invention in whichthe vehicle module 103 spacing within the load handling device 100remains constant and the container receiving platform 198 comprises twoportions. A first portion of the platform 198 is moveable relative tothe second portion of the platform 198 such that in use, the fixedposition vehicle modules 103 lower the containers 106 on to the portionsof the platform 198 by means of the container lifting device and gripper110 mechanism. A portion of the platform 198 moves so as to enable thedelivered containers 106 to be transferred to the shipping trolley 202.

It will be appreciated that the load handling device 100 and thecontainer receiving platform 198 are acting so as to adjust the pitch orspacing of the containers 106 to enable mismatches between containerstack 12 pitch and shipping trolley container pitch 110. However, itwill be appreciated similar method and apparatus may be used tocompensate for a mismatch in spacing or pitch at other points in theprocess or system.

It will be appreciated that many different variations and modificationsare possible. For example, both sets of wheels may be powered by asingle motor, with a suitable transfer arrangement to direct power tothe appropriate set of wheels. Instead of a motor, the mechanism used tolift the wheels may use linear actuators, such as linear motors orhydraulic rams.

The mechanism used to lift containers into the container-receiving spacecould take any suitable form. For maximum stability and load capacity,it is desirable to provide four lifting cables, with one cable disposednear each of the corners of the device, but a different arrangement, forexample with fewer cables, could be used if desired. Conveniently, allof the cables are spooled and unspooled using a single motor, but morethan one motor could be used if desired.

It will be appreciated that that the individual lifting mechanisms maybe configured so as to lift a larger container, said larger containerbeing of equivalent footprint to an integer number of containers.

Other variations and modifications not explicitly described above willalso be apparent to the skilled reader.

1. A load handling device for retrieving, transporting, and deliveringcontainers in a storage system, the storage system having a gridstructure formed of two substantially perpendicular sets of rails ortracks, the grid structure forming a plurality of grid spaces andlocated above a plurality of stacks of one or more containers, eachstack arranged to occupy a footprint of a single grid space, the loadhandling device configured to move laterally on rails or tracks abovestacks of containers, the load handling device including: a wheelassembly, the wheel assembly comprising a first set of wheels forengaging with a first set of rails or tracks of the plurality of railsor tracks to guide movement of the load handing device in a firstdirection and a second set of wheels for engaging with a second set ofrails or tracks of the plurality of rails or tracks to guide movement ofthe load handing device in a second direction; a container receivingspace; a plurality of vehicle modules, each of the vehicle moduleshaving a container lifting means arranged to lift a container such thatthe load handling device is arranged to lift a corresponding number ofcontainers as vehicle modules into the container receiving space; andwherein each of the vehicle modules are moveable to adjust the spacingof the containers in the load handling device.
 2. A load handling deviceaccording to claim 1, wherein each of the vehicle modules are moveableaxially towards and/or away from each other so as to adjust the spacingof the containers in the load handling device.
 3. A load handling deviceaccording to claim 1, wherein the lifting means of two or more of theplurality of vehicle modules are arranged to lift a larger container,the larger container being of equivalent footprint to an integer numberof containers.
 4. A load handling device according to claim 1, whereinthe wheels are mounted to fixed T-pieces disposed at either end of theload handling device.
 5. A load handling device according to claim 1,wherein at least the first or the second set of wheels have a toothedcentral channel that forms a pulley for cooperating with a drive belt.6. A load handling device according to claim 5, wherein the toothedcentral channel is bounded by two rubber tires configured to bear uponthe rails or tracks so as to keep the drive belt in alignment.
 7. A loadhandling device according to claim 6, wherein the at least first orsecond set of wheels comprising the toothed central channel is mountedto an arm by an axle that extends through an axial hole in the wheel. 8.A load handling device according to claim 1, including: an upper part,the upper part housing power components, control components, drivecomponents and/or lifting and lowering components; and a lower part, thelower part including the container receiving space, and wherein thelower part is arranged directly below the upper part.
 9. A load handlingdevice according to claim 7, wherein the wheels, the drive belt, therubber tires, the arm, and the axle are arranged around the edges of thecontainer receiving space so that an upper part of the load handlingdevice is solidly supported, the upper part housing power components,control components, drive components and/or lifting and loweringcomponents, the upper part arranged directly above a lower part housingthe container receiving space.
 10. A storage system comprising: a gridstructure formed of two substantially perpendicular sets of rails ortracks, the grid structure forming a plurality of grid spaces; aplurality of stacks of one or more containers located beneath the railsor tracks, each of the plurality of stacks and arranged such that eachstack occupies a footprint of a single grid space; and a load handlingdevice, the load handing device including: a wheel assembly, the wheelassembly comprising a first set of wheels for engaging with a first setof rails or tracks of the plurality of rails or tracks to guide movementof the load handing device in a first direction and a second set ofwheels for engaging with a second set of rails or tracks of theplurality of rails or tracks to guide movement of the load handingdevice in a second direction, a container receiving space, a pluralityof vehicle modules, each of the vehicle modules having a containerlifting means arranged to lift a container such that the load handlingdevice is arranged to lift a corresponding number of containers asvehicle modules into the container receiving space, and wherein each ofthe vehicle modules are moveable to adjust the spacing of the containersin the load handling device.
 11. A storage system according to claim 10,including: a port location, the port location having container receivingmeans, the container receiving means including: a container receivingplatform; a transferring means; and wherein the container receivingplatform and the transferring means together being adapted to receive aplurality of containers delivered by the load handing device andtransfer the plurality of containers to a shipping trolley.
 12. Astorage system according to claim 11, wherein each of the plurality ofthe vehicle modules are moveable to enable the containers to bedelivered onto the container receiving platform in a position enablingthe transfer means to relocate the delivered containers onto theshipping trolley.
 13. A storage system according to claim 11, whereineach of the plurality of the vehicle modules are moveable such that thespacing of the containers in the load handling device matches thespacing of container receiving shelves of the shipping trolley.
 14. Astorage system according to claim 10, wherein the lifting means of twoor more of the plurality of vehicle modules are arranged to lift alarger container, the larger container being of equivalent footprint toan integer number of containers.
 15. A storage system according to claim10, wherein the wheels of the load handling device are mounted to fixedT-pieces disposed at either end of the load handling device.
 16. Astorage system according to claim 10, wherein at least the first or thesecond set of wheels of the load handling device have a toothed centralchannel that forms a pulley for cooperating with a drive belt.
 17. Astorage system according to claim 16, wherein the toothed centralchannel is bounded by two rubber tires configured to bear upon the railsor tracks so as to keep the drive belt in alignment.
 18. A storagesystem according to claim 16, wherein the at least first or second setof wheels comprising the toothed central channel is mounted to an arm byan axle that extends through an axial hole in the wheel.
 19. A storagesystem according to claim 10, wherein the load handling device includes:an upper part, the upper part housing power components, controlcomponents, drive components and/or lifting and lowering components; anda lower part, the lower part including the container receiving space,and wherein the lower part is arranged directly below the upper part.20. A method of transferring a plurality of containers located within aplurality of adjacent stacks in a storage system from the storage systemto a shipping trolley via a load handling device, the method comprising:retrieving, by the load handling device, a plurality of containers froma correspondingly numbered plurality of stacks, wherein the loadhandling device retrieves the plurality of containers using a pluralityof lifting means in a single operation, each of the plurality of liftingmeans configured to lift a container of the plurality of containers intoa container receiving space of the load handling device; transporting,by the load handling device, the plurality of containers from theplurality of stacks to a port location; delivering, by the load handlingdevice, the plurality of containers to the port location; and lowering,by the load handling device, the plurality of containers via theplurality of lifting means on to a container receiving platform, whereinthe container platform transfers the plurality of containers to theshipping trolley.